Up to half a million lives could be saved over the next decade by small, steady reductions in the national salt intake, computer simulations suggest.

Action Points

Note that this simulation study suggests that significantly cutting national sodium consumption would result in a substantial number of lives saved.

Be aware that even the most conservative model -- gradually cutting sodium consumption by 40% over 10 years -- would be difficult to achieve without large-scale intervention.

Up to half a million lives could be saved over the next decade by small, steady reductions in the national salt intake, computer simulations suggest.

Gradually cutting sodium consumption by 4% annually to reach 2,200 mg per day by 10 years would prevent 275,000 to 505,000 deaths over that span, depending on the modeled assumptions, Pamela G. Coxson, PhD, of the University of California San Francisco, and colleagues found.

Immediately dropping to the 1,500 mg per day level recommended by federal dietary guidelines would save 1.2 million lives over 10 years, they reported in the March issue of Hypertension.

That rapid a degree of reduction from the current national average of 3,600 mg per day isn't feasible, and even a 40% reduction over a decade would be "a daunting task that will likely require multiple layers of intervention," the group acknowledged.

Dietary salt reduction has been controversial, with a full gamut of study findings from negative to neutral to positive along with pushback from the salt industry arguing that the 1,500-mg intake guidelines should have been only for high-risk groups, not the general population.

To help build consensus about what the population-level benefit might be, Coxson's group used a variety of modeling methods on three different scenarios:

Gradual reduction of individual sodium intake by 40% over 10 years to an average 2,200 mg per day, which is what would be achieved by cutting sodium in processed and commercially prepared foods by half

Instantaneous 40% reduction in sodium consumption sustained for 10 years

Instantaneous reduction to an average of 1,500 mg per day, the target recommended for most adults in the 2010 U.S. Dietary Guidelines for Americans

The first scenario "is optimistic but potentially achievable," the researchers argued, pointing to the steady 3% to 4% per year reductions in salt intake achieved by a British salt reduction initiative and the 20% to 30% reduction achieved over 20 years by a public campaign in Finland.

The other two scenarios were maximum mortality benefit estimates for meeting targets.

The biggest gains were seen in models based on the direct effect of a low-sodium diet on heart disease events in the Trial of Hypertension Prevention, which had about twice the impact of two other models based on indirect effects via blood pressure lowering.

So the instantaneous reduction to 1,500 mg per day with the direct effect model suggested a more than 20% reduction in cardiovascular disease deaths, for an absolute benefit of 1.2 million fewer deaths over 10 years, while the same scenario with the blood pressure-mediated models suggested about a 10% reduction in cardiovascular disease deaths, for an absolute 644,000 to 731,000 lives saved over 10 years.

Instantly reaching the more modest target of 40% sodium intake reduction was projected to have about a 25% lower impact on total mortality, for 488,000 to 874,000 lives saved over a decade.

The more gradual route to that target had half the impact of an instantaneous change, for a 4% to 10% reduction in coronary heart disease and stroke mortality and a 1.5% to 3% reduction in total mortality.

The researchers acknowledged varying complexity and associated biases in the three models, and the attenuated associations in a sensitivity analysis in which those 75 and older were assumed to get no benefit from lowering sodium intake.

Nevertheless, "the large health benefit from sodium reduction that we project here and find to be robust to a variety of different assumptions about the effect of sodium on cardiovascular health and different approaches to computer simulation suggests that sodium reduction is an important target for public health interventions," they wrote.